South Bend Lathe – Chuck and collets

[Matt Stevens 1Participant @mattstevens1]

[Matt Stevens 1Participant @mattstevens1]

So I have a 1939 Model C South Bend. My 3-jaw chuck is not exactly the most accurate and I wonder the best way to improve this…..I have bored it out slightly, but the jaws were not clamped in anyway – mainly because the jaws are hardened and therefore near impossible to drill to fit a clamp to.

Buying a new chuck is very expensive….so maybe I can just change the jaws? Is there anything special I need to be aware of when searching for new jaws?

Collets – My mill has R8 style collets and so I guess it would be great if I could re-use those on my lathe somehow. I have a feeling the lathe might be M3 (would need to check). Has anyone made any converter? Any hints/tips?

I guess I would also need something to screw onto the headstock to pull in the collet?

[Chris Evans 6Participant @chrisevans6]

When I had a South Bend "Heavy 10" of 1942 vintage (mine for 45 years) it used 5C collets with a draw bar through the spindle. Jaws for your chuck are going to be hard to find until you can identify the make of chuck and find a supplier. If you do identify the chuck try Rotagrip in Birmingham. It may still be cheaper to buy a new imported chuck. I have been quoted £164 for a set of jaws for my 160mm chuck which is about the same as an imported chuck with integral D 14 camlock mount.

[mark smith 20Participant @marksmith20]

Your lathe will have a 3mt probably and the bore is probably small ,my 9a has 3 c collets and i think they only go up to about 1/2".

I would find a 3mt ER collet chuck of some sort and make some sort of drawbar out of threaded rod .

http://www.arceurotrade.co.uk/Catalogue/Collets/ER-Milling-Collet-Chucks-Morse-Taper-Shank/ER40-Milling-Collet-Chucks

or try one of these but you`ll need a threaded backing plate to fix it to.

http://www.arceurotrade.co.uk/Catalogue/Collets/ER-Lathe-Collet-Chucks/ER32-Lathe-Collet-Chucks

Edited By mark smith 20 on 28/11/2016 19:32:47

[BazyleParticipant @bazyle]

R8 are going to be too big to fit in an MT3 spindle and rather long for an adaptor. As mentioned the standard fit is 3C. But have a think about what sizes you really need. If only a few an MT3to2 adaptor plus MT2 collets are fairly cheap from Arc. You will find it is the scroll in the chuck as much as the jaws that are worn. Regrind to remove bell mouth but it still won't be concentric. Just use shims when needed.

I've just had this idea for holding the jaws firm when regrinding. Take them out and measure the offset of the 'teeth' relative to one another. Make a 'spider' with 3 thin legs to match which you can insert in the middle just beyond the jaw gripping face so it bears against the front tooth. Set screws might do for the legs. You might also push the spider from behind so it cants the jaws outward in the slop of the slide as if gripping a short item in the front of the chuck.

By the way I think Harold Hall has details of how to make new jaws on his website.

Edited By Bazyle on 28/11/2016 20:02:00

[Neil WyattModerator @neilwyatt]

If you google '3-jaw grinding spacer' you will see various types of spacer people have used to get the jaws in position for truing up.

Neil

[Paul LousickParticipant @paullousick59116]

Matt,

Jaws come with a chuck as a matched set and are numberred for fitting to a particular slot. Purchasing new jaws may not solve your problem which cauld also be caused by wear in the scroll.

A post about jaw grinding was coverred in a previous post under "New three jaw chuck" (see link below)

Paul.

**LINK**

[Matt Stevens 1Participant @mattstevens1]

Thanks for all the comments guys….

For the record, I am based in Ontario Canada.

I have googled the spaced idea – as usual, so simple once someone has pointed it out to you! I will check the runout of my chuck and see how much is to be gained by grinding. I would have to make a fixture for a start to hold my dremel!.

For the collets – again the Drawbar seems the sensible way to go. As Mark Smith pointed out he has a 9a model, that will be the same as my 9c….so I am confident to say I will likely need 3C collets I guess.

The ER collet solution looks interesting, but I guess this route is also more expensive?!

Perhaps I will keep an eye open for a 3C collet set on ebay!

Thanks

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